Liver carcinogenesis: A small electrophoretic class of soluble proteins of target organs contains the principal protein-carcinogen conjugates of three families of carcinogens. In pursuit of the possible role in carcinogenesis of one such conjugate, and of the interaction between carcinogen and target protein from which it arises, the following are broad aims of the proposed research: 1. Characterization of the principal soluble liver azoprotein of azo dye preneoplastic liver. 2. Identification of the principal protein target of azocarcinogens in liver. Cell transformation to malignancy: The goal is to investigate the extracellular fibrinolytic activities that may be associated with cells oncogenically transformed by viruses or chemicals. Neoplastically transformed cells will be investigated, in order to ascertain whether or not their tumorigenicity in immune-deficient mice is related to an enhanced fibrinolytic activity of these cells.